There are many applications for detecting when a human user is looking directly at a device. One such application is self-service kiosks. The kiosk may be in a general attention attracting mode with flashy graphics until someone actually looks at the device. At this point, it may launch a targeted promotion because it has the user's attention.
Kiosks can also be activated by simple proximity sensors or by machine vision systems employing techniques such as background subtraction. However, these solutions only assure that a person is nearby, not that he is looking at the device.
Another application is operator alertness monitoring. At regular intervals the operator of a machine may be required to look at various task-relevant areas or directions. For instance, an alert driver of a car needs to look forward through the windshield and occasionally at the rearview mirror. If this does not occur, or only one point is looked at, the driver may have become drowsy. The proper alternation of gaze can be determined by placing a gaze detector at each special point, i.e., the base of the windshield and in the rearview mirror.
There are also a number of driver alertness systems. Many of these are based on blink frequency or eyelid closing rate. As such, they do not ensure that a driver is paying attention to the important aspects of his environment (e.g., he may be facing the passenger).
There are many eye-tracking devices on the market. However, many of them must be worn by the user. Others are bulky or have a limited range of acceptable positions for the user's head.